No Mega the Cold War was won in the '80s. The military was behind the curve in the '80s and tried to catch up to our "offensive threat" which they never managed to do by the time the game was up in 1989. Reagan's military program roared ahead as early as '81 and caught the Soviets off guard.
As for Beirut, Reagan did something that was very new which was "peace keeping". We sent troops and so did the French to try and separate the warring factions fighting since '75. Nobody had any idea that we would end up being the targets. We know about the dangers of peace keeping today but were clueless in 1983.
Regan had no choice to "cut and run". As you may remember, Vietnam was very fresh in the minds of Americans and nobody wanted another mission without an exit strategy. So he "cut".
